SOLUTION: In a science test, a class of 30 students had an average of 80. The 20 girls in the class had an average of 85. What is the average of the 10 boys in the class?

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Question 312379: In a science test, a class of 30 students had an average of 80. The 20 girls in the class had an average of 85. What is the average of the 10 boys in the class?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let B be the boys' scores, G be the girls' scores.
%28B%2BG%29%2F30=80
1.B%2BG=2400
.
.
G%2F20=85
2.G=1700
Then from eq. 1,
B%2BG=2400
B%2B1700=2400
B=700
Since there are 10 boys, then
Y=700%2F10=70
The boys had an average of 70 on the test.